Apollo Expeditions to the Moon

CHAPTER 3.6

ARTIFICIAL STORMS AT THE ARM FARM

The connections between the ground and the towering space vehicle posed a tricky
problem. An umbilical tower, even higher than the vehicle itself, was required to
support an array of swingarms that at various levels would carry the cables and the
pneumatic, fueling, and venting lines to the rocket stages and to the spacecraft. The
swingarms had to be in place during final countdown, but in the last moments they had to be
turned out of the way to permit the rocket to rise. There was always the possibility,
however, of some trouble after the swingarms had been disconnected. For instance, the
holddown mechanism would release the rocket only after all five engines of the first
stage produced full power. lf this condition was not attained within a few seconds, all
engines would shut down. In such a situation, unless special provisions were made for
reattachment of some swingarms, Launch Control would be unable to "safe" the vehicle
and remove the flight crew from its precarious perch atop a potential bomb.

These considerations led to the establishment, at Marshall, of a special Swingarm
Test Facility, where detachment and reconnection of various arms was tested under
brutally realistic conditions. On the "Arm Farm" extreme conditions (such as a launch
scrub during an approaching Florida thunderstorm) could be simulated. Artificial rain
was blown by aircraft propellers against the swingarms and their interconnect plugs,
while the vehicle portion was moved back and forth, left and right, simulating the swaying
motions that the towering rocket would display during a storm.

Throughout Saturn V's operational life, its developers felt a relentless pressure to
increase its payload capability. At first, the continually growing weight of the LM
(resulting mainly from additional operational features and redundancy) was the prime
reason. Later, after the first successful lunar landing, the appetite for longer lunar stay
times grew. Scientists wanted landing sites at higher lunar latitudes, and astronauts
like tourists everywhere wanted a rental car at their destination. How well this growth
demand was met is shown by a pair of numbers: The Saturn V that carried Apollo 8
to the Moon had a total payload above the IU of Iess than 80.000 pounds; in
comparison, the Saturn that launched the last lunar mission, Apollo 17, had a payload of
116,000 pounds.

Silhouetted by the glare of the first Saturn V launch, a flock of
birds calmly conducts its dawn patrol of the lagoon. As the vehicle
begins to clear the launch pad, several more seconds will pass before
the crashing roar reaches the flock. This is Apollo 4, the first
"all up" test of the launch vehicle and spacecraft, proving out their
flight compatibility in an unmanned Earth-orbiting mission.